This invention relates to a tape drive for driving a tape cartridge such as a linear tape storage system represented by DLT (digital liner tape) or LTO (linear tape open) and, in particular, to a reel hub lock releasing mechanism for releasing lock of a reel hub in the tape cartridge.
Linear tape storage systems of the type described are developed as xe2x80x9cback-upxe2x80x9d systems for hard disks of computer systems and various types of the linear tape storage systems have been proposed in prior art. For example, a digital linear tape drive serving as the DLT is disclosed in U.S. Pat. No. 5,862,014 to Nute, entitled: xe2x80x9cMulti-Channel Magnetic Tape Head Module Including Flex Circuitxe2x80x9d or the like.
The digital linear tape drive (which may be merely called xe2x80x9cdriving apparatusxe2x80x9d, xe2x80x9ctape drivexe2x80x9d, or xe2x80x9cdrivexe2x80x9d) is for receiving a tape cartridge (which may be merely called xe2x80x9ccartridgexe2x80x9d) having a single reel (a supply reel) and contains a take-up reel therein. When the tape cartridge is installed in the driving apparatus, a magnetic tape is pulled out of the tape cartridge and then is wound by the take-up reel through a head guide assembly (HGA). The head guide assembly is for guiding the magnetic tape (which may be merely called xe2x80x9ctapexe2x80x9d) pulled out of the tape cartridge in a magnetic head. The magnetic head exchanges information between the tape and the magnetic head. The head guide assembly generally comprises a boomerang-shaped aluminum plate and six large guide rollers each using a bearing.
In addition, the head guide assembly is also called a tape guide assembly which is disclosed, for example, in U.S. Pat. No. 5,414,585 to Saliba, entitled: xe2x80x9cRotating Tape Edge Guide.xe2x80x9d In addition, an example of the guide roller is disclosed in Japanese Unexamined Patent Publication Tokkai No. 2000-100025 or JP-A 2000-100025.
The tape drive is generally comprised of a rectangular housing that has a common base as described, for example, in U.S. Pat. No. 5,793,574, entitled: xe2x80x9cTape Head Actuator Assembly Having A Shock Suppression Sleevexe2x80x9d to Cranson et al. The base has two spindle motors (reel motors). The first spindle motor has a spool (or a take-up reel) permanently mounted on the base and the spool is dimensioned to accept a relatively high speed streaming magnetic tape. The second spindle motor (reel motor) is adapted to accept a removable tape cartridge. The removable tape cartridge is manually or automatically inserted into the drive via a slot formed on the drive""s housing. Upon insertion of the tape cartridge into the slot, the cartridge engages the second spindle motor (reel motor). Prior to rotation of the first and the second spindle motors, the tape cartridge is connected to the permanently mounted spool (the take-up reel) by means of a mechanical buckling mechanism. A number of rollers (guide rollers) positioned intermediate the tape cartridge and the permanent spool guide the magnetic tape as it traverses at relatively high speeds back and forth between the tape cartridge and the permanently mounted spool.
In the digital linear tape drive having such a structure, an apparatus for pulling the tape from the supply reel to the take-up reel is required. Such as a pulling apparatus is disclosed, for example, in International Publication Number WO 86/07471. According to WO 86/07471, take up leader means (a first tape leader) is coupled to the take-up reel while supply tape leader means (a second tape leader) is connected to the tape on the supply reel. The first tape leader has one end formed into a mushroom like tab. The second tape leader has a locking aperture. The tab is engaged into the locking aperture.
Furthermore, a mechanism for joining or coupling the first tape leader with the second tape leader is required. Such a joining or coupling mechanism is disclosed, for example, in International Publication number WO 86/07295.
In addition, Japanese Unexamined Patent Publication Tokkai No. 2000-100116 or JP-A 2000-100116 discloses a structure of leader tape engaging part which can engage an end part of a leader tape (the second tape leader) to a tape end hooking part in a tape cartridge without requiring a tab projected in the side of the leader tape.
U.S. Pat. No. 5,857,634, entitled: xe2x80x9cTake-up Reel Lockxe2x80x9d to Hertrich discloses a locking system for preventing a take-up reel of a tape drive from rotating when a tape cartridge is not inserted to the drive.
On the other hand, an example of the tape cartridge installed in the digital linear tape drive is disclosed in Japanese Unexamined Patent Publication Tokkai No. 2000-149491 or JP-A 2000-149491.
In addition, U.S. Pat. No. 6,241,171, entitled: xe2x80x9cLeaderless Tape Drivexe2x80x9d to Gaboury discloses a tape drive wherein a tape leader from a tape cartridge is urged through a tape path, into a take-up reel, and secured therein without the use of a bucking mechanism or a take-up leader.
In addition, the tape drive further comprises a tape head actuator assembly which is located between a take-up spool and a tape cartridge on a tape path defined by a plurality of rollers. During operation, a magnetic tape flows forward and backward between the take-up spool and the tape cartridge and is closely adjacent to the tape head actuator assembly while the magnetic tape flows on the defined tape path. An example of such as a tape head actuator assembly is disclosed in the above-mentioned U.S. Pat. No. 5,793,574.
Now, as is disclosed in the above-mentioned JP-A 2000-149491, the tape cartridge comprises a case and a rotary reel (a supply reel) which is rotatably stored in the case and which winds a recording/reproducing magnetic tape therearound. In such as a tape cartridge, it is necessary to stop rotational driving of the supply reel in a state where the tape cartridge is not inserted in the slot of the tape drive. Otherwise, there is fear of inconvenience occurring such that the magnetic tape breaks out of the tape cartridge to the exterior caused by rotation of the supply reel in the tape cartridge when the tape cartridge is carried or the like. For this purpose, the tape cartridge contains a reel hub lock mechanism for locking a reel hub of the supply reel. Such as a lock in the reel hub of the supply reel is called a xe2x80x9creel hub lockxe2x80x9d in the art. That is, the tape cartridge is put into a state where the reel hub of the supply reel is made in the reel hub lock by the reel hub lock mechanism when it is not inserted in the slot of the tape drive. The reel hub lock mechanism includes a lock lever for enabling to release the reel hub lock by operating the lock lever from the exterior.
On the other hand, the tape drive requires a mechanism for releasing the reel hub lock by operating the above-mentioned lock lever when or after the tape cartridge is inserted in the slot. Such as a mechanism is called a xe2x80x9creel hub lock releasing mechanism.xe2x80x9d More specifically, the tape drive comprises a loading mechanism for engaging the supply reel with the supply reel motor after the tape cartridge is inserted in the slot. The loading mechanism comprises a loading motor mounted on the chassis and a ring cam driven by the loading motor. The ring cam is coaxial with a rotation axis of the supply reel motor and is rotatably disposed between a back surface of the chassis and the supply reel motor. The ring cam has a cam groove. The reel hub lock releasing mechanism comprises a release lever having an engaging projection for engaging with the cam groove of the ring cam. When the tape cartridge is inserted in the slot, the reel hub lock releasing mechanism releases, in response to rotation of the ring cam, the reel hub lock by operating the lock lever.
In the manner which will later be described in conjunction with FIGS. 1 through 5, in a conventional reel hub lock releasing mechanism, a load is always applied to the ring cam by a spring. Accordingly, the loading motor for driving the ring cam must operate in opposition of this load. Therefore, a larger one is required as the loading motor and a life of the loading motor becomes shorter. In addition, inasmuch as a friction force based on the engaging projection of the release lever is exerted on the cam groove of the ring cam caused by the spring. Furthermore, inasmuch as the release lever consisting the reel hub lock releasing mechanism itself has long and large size which extends from a front side of the tape drive to a center rear side thereof, it is difficult to miniaturize the reel hub lock releasing mechanism. In addition, inasmuch as the reel hub lock releasing mechanism is composed of a lot of parts such as the release lever, a fulcrum shaft, and the spring, it is difficult to decrease the number of the parts and assembling thereof is complicated. As a result, it is really difficult to reduce costs of the reel hub lock releasing mechanism.
It is therefore an object of the present invention to provide a reel hub lock releasing mechanism which is capable of minimizing a loading motor and of lengthening the life of the loading motor.
It is another object of the present invention to provide a reel hub lock releasing mechanism of the type described, which is capable of decreasing friction to a ring cam.
It is still another object of the present invention to provide a reel hub lock releasing mechanism of the type described, which is capable of simplifying assembling of the reel hub lock releasing mechanism by decreasing the number of parts.
On describing the gist of an aspect of this invention, it is possible to be understood that a reel hub lock releasing mechanism is for use in a tape drive. The tape drive comprises a chassis having a main surface and a back surface, a take-up reel rotatably mounted on the main surface of the chassis, a take-up reel motor mounted on the back surface of the chassis for rotatably driving the take-up reel, a slot disposed on the main surface of the chassis for inserting a tape cartridge containing a supply reel, a supply reel motor mounted on the back surface of the chassis at a position opposed to the slot for rotatably driving the supply reel in the tape cartridge, and a loading mechanism for engaging the supply reel with the supply reel motor after the tape cartridge is inserted in the slot. The loading mechanism includes a loading motor disposed on the chassis and a ring cam operatively driven by the loading motor. The ring cam is coaxial with a rotation axis of the supply reel motor. The ring cam is rotatably disposed between the back surface of the chassis and the supply reel motor. The ring cam has a cam groove. The tape cartridge is put into a reel hub locked state where a reel hub of the supply reel is locked by a reel hub lock mechanism to stop rotation of the supply reel when the tape cartridge is not inserted in the slot. The reel hub lock mechanism includes a lock lever for enabling to release a reel hub lock by operating the lock lever from the exterior. The reel hub lock releasing mechanism is for releasing the reel hub lock by operating the lock lever in response to rotation of the ring cam when the tape cartridge is inserted in the slot. According to the aspect of this invention, the reel hub lock releasing mechanism comprises a seesaw-type release lever rotatably disposed on the back surface of the chassis around a fulcrum part at a center thereof. The seesaw-type release lever comprises first and second plate bodies extending from the fulcrum part toward both sides. The first plate body has, at a tip thereof, an engaging projection engaged with the cam groove of the ring cam. The second plate body has, at a tip thereof, a lever operating projection which projects upward to operate the lock lever. The reel hub lock releasing mechanism further may comprise a spring, disposed around the fulcrum part, for preventing a part from falling away to fit the seesaw-type release lever to the chassis.